I used to think that Parliament would be a better place if it had more scientifically trained politicians, but have watched the furore occurring around Darren Hughes and the Labour party, I think I see why very few politicians have scientific training – the thought processes needed for each career are diametrically opposed.
Scientists train to be as objective as they can be, to remove as much bias as is possible from their experiments. Facts are the currency of science. Politicians, however, realise that when it comes to dealing with people, emotions are an effective way of swaying public opinion. Personal attacks, innuendo and rumour are all part of the game. In politics perception is everything. Opinions are the currency of politics.
This is not to say that politicking does not occur in scientific organisations. I learnt this fairly early in my PhD. However, in the practice of science, when you are working in the lab, it is the facts and not opinion that are important.
For a scientist to enter the world of politics he or she has to be prepared to turn his/her back on the thought processes that are central to science. This is not a choice I could see myself making.